Uptake and distribution of fluopyram and tebuconazole residues in tomato and bell pepper plant tissues

Abstract

The present study describes the uptake and distribution of fungicides, fluopyram, and tebuconazole in tomato and bell pepper plant tissues from the soil drench application of their combination product fluopyram17.7% + tebuconazole 17.7%. For extraction and cleanup of fluopyram, its metabolite fluopyram benzamide, and tebuconazole samples, the QuEChERS method was used in conjunction with LC-MS/MS. The limit of detection (LOD) and limit of quantification (LOQ) of the method determined were 1.5 μg kg⁻¹ and 0.005 mg kg⁻¹, respectively, and recoveries of all analytes from sample matrices remained within the acceptable range of 70–120%. Rapid uptake of the fungicides by tomato and bell pepper plants was observed from the first day onwards. In the tomato plant, the major part of the fungicides accumulated in the roots, whereas in bell pepper plant, it accumulated both in the roots and in the leaves. Accumulation of fluopyram and tebuconazole residues was lowest in tomato and bell pepper fruits which were much below their respective maximum residue limits (MRLs). The highest residue concentration of fluopyram and tebuconazole in tomato fruits was 0.060 and 0.009 mg kg⁻¹; the corresponding values in bell pepper fruits were 0.080 and 0.013 mg kg⁻¹. In field soil, fluopyram residues were 3.18–3.570 mg kg⁻¹ initially which dissipated at the half-life of 36 days. Tebuconazole concentration was 1.57–1.892 mg kg⁻¹ initially, and it dissipated at the half-life of 44.5–49.5 days. The major metabolite of fluopyram, fluopyram benzamide, was detected in plant tissues as well as in soil, and remained within 12% of the parent compound. The results of the study indicated that fluopyram and tebuconazole are less likely of entry into food chain through intake of tomato and bell pepper fruits if these crops are grown on soil contaminated with these fungicides.